Fig. 5.

The adult haemangioblast genetic regulatory network. Network summarising the genetic interactions programming adult haemangioblasts in the DLP as determined by MO knockdown. Strikingly, somitic VEGFA is absolutely essential for Flk1 receptor activation in haemangioblast precursors; this activation results in the establishment of endogenous, cell-autonomous VEGFA signalling. Importantly, Scl expression and haemangioblasts cannot be specified unless this endogenous VEGFA signalling synergises with a VEGFA-independent pathway controlled by Fli1 and Etv2. The timing and tissue of expression is denoted by the position of the gene on the network, whereas its relationships with genes expressed at the same time or later is depicted by an arrow from the regulating gene to the regulated gene. Arrows with chevrons indicate the interaction between VEGFA and its receptor, Flk1. P indicates paracrine VEGFA signalling, whereas A indicates endogenous autocrine signalling. The red circle represents the formation of a well-characterised protein complex between Scl and Lmo2.